1. Field of the Invention
The present invention relates to a submount for an opto-electronic module and a packaging method using the same, and more particularly, to a submount for an opto-electronic module suitable for high-speed transmission and a packaging method using the same.
2. Description of the Related Art
Recently, as the demand for high-quality communication service increases sharply, the transmission speed of optical communication systems becomes very rapid. Now, it is possible to build a comprehensive network having an ultrahigh speed broad-band width using opto-electronic modules having a unit transmission speed of 2.5 Gbps in systems having a transmission speed of about 40-100 Gbps by Wavelength Division Multiplexing (WDM). However, opto-electronic modules having the minimum unit transmission speed of 10 Gbps are required to increase the efficiency of the configuration of optical communication systems having a transmission speed of 160-640 Gbps.
FIG. 1 is an exploded perspective view of a general photo-receiver module including a general submount for an opto-electronic module. Referring to FIG. 1, a submount 104, to which an opto-electronic device 102 such as a photodiode sticks, is attached to a substrate 106. The submount 104 electrically connects the opto-electronic device 102 to an electronic device (not shown) on the substrate 106 using wires or ribbon bonding. A plurality of signal lines 108 are installed on the substrate 106 for such electrical connection. An amplifier 110 for amplifying an electrical signal output from the opto-electronic device 102 to a predetermined level or above is attached to the substrate 106. The amplifier 110 electrically contacts the plurality of signal lines 108 on the substrate 106. The substrate 106, to which the submount 104 and the amplifier 110 are attached, is put into a metal shield case 112 and then the metal shield case 112 is covered with a cover 113. An optical fiber 114, which forms a path of light incident on the opto-electronic device 102, penetrates through the metal shield case 112 and is aligned with the opto-electronic device 102 so that light is properly incident on the opto-electronic device 102. For this, a fiber support 116 is attached to the substrate 106 to support the optical fiber 114.
In this general photo-receiver module, the submount 104 is connected to the electronic device (not shown) mainly using bonding wires. However, if the general photo-receiver module having the above-described configuration is a photo-receiver module having a transmission speed of 2.5 Gbps or more, signal distortion occurs on interconnection lines between the opto-electronic device 102 and the electronic device (not shown) due to parasitic components of the bonding wires. As a result, the reliability of signal transmission and the reliability of module operation are reduced. Moreover, there is a limit in that additional interconnection lines installed on the submount 104 are not used in a photo-receiver module requiring high-speed operation of over 2.5 Gbps.
To solve the above-described problems, it is a first object of the present invention to provide a submount for an opto-electronic module suitable for high-speed transmission of over 2.5 Gbps.
It is a second object of the present invention to provide a packaging method using the submount for an opto-electronic module.
Accordingly, to achieve the first object, there is provided a submount for an opto-electronic module for outputting light incident from an opto-electronic device as an electrical signal. The submount includes a dielectric material having a polygonal shape with a front face and a bottom face, and an interconnection line having a coplanar waveguide structure, attached to the front face and the bottom face of the dielectric material, and electrically connected to the opto-electronic device to output signals from the opto-electronic device.
It is preferable that the interconnection line having a coplanar waveguide structure includes a plurality of interconnection lines, which are spaced apart from each other. The the interconnection lines may be a first ground line, a signal transmission line, a second ground line, and a bias application line, respectively, which are sequentially disposed. It is preferable that the the opto-electronic device is attached to a portion of the second ground line, which is attached to the front face of the dielectric material. The opto-electronic device attached to the second ground line is preferably connected to the signal transmission line and the bias application line via wires.
It is preferable that the distance between a portion of the signal transmission line and a portion of the second ground line on the bottom face of the dielectric material is greater than the distance between a portion of the signal transmission line and a portion of the second ground line on the front face of the dielectric material.
To achieve the second object, there is provided a packaging method using a submount for an opto-electronic module including a dielectric material and an interconnection line having a coplanar waveguide structure. An opto-electronic device is attached to the interconnection line to be electrically connected to the interconnection line. The interconnection line, to which the opto-electronic device is attached, is attached to a conductive interconnection line of a substrate.
Attaching the interconnection line to the conductive interconnection line of the substrate is performed using conductive epoxy.